Method and apparatus for controlling call volume in a packet network

ABSTRACT

Method and apparatus for controlling call volume in a packet-switched network is described. In one example, a number of concurrent calls per codec of a plurality of codecs is monitored. A concurrent call limit for each of the plurality of codecs is obtained. For each codec of the plurality of codecs, an indication is generated for each call causing the number of concurrent calls for the codec to exceed the concurrent call limit for the codec. In response to the indication, the call may be blocked or an alternative codec may be selected for the call.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the present invention generally relate totelecommunications systems and, more particularly, to a method andapparatus for controlling call volume in a packet network.

2. Description of the Related Art

Generally, telecommunications systems provide the ability for two ormore people or machines (e.g., computerized or other electronic devices)to communicate with each other. A telecommunications system may includevarious networks for facilitating communication that may be generallyorganized into packet networks and circuit-switched networks. Anexemplary circuit-switched network includes a plain old telephone system(POTS), such as the publicly switched telephone network (PSTN).Exemplary packet networks include internet protocol (IP) networks,asynchronous transfer mode (ATM) networks, frame-relay networks, and thelike. One type of packet network is a voice-over-internet protocol(VOIP) network.

VOIP network providers often provide support for multiple coder-decoders(codecs). Codecs are used to code and decode media data (e.g., voice)communicated during a call among endpoints. Multiple codec support in aVOIP network accommodates the needs of an array of customer segments,from wholesale customers to enterprise customers to individualconsumers. However, engineering network elements to meet therequirements of these codecs can be problematic. Notably, calls usingsome codecs consume more bandwidth and network resources than callsusing other codecs. Too many calls using high-bandwidth codecs candecrease performance of the VOIP network. Accordingly, there exists aneed in the art for an improved method and apparatus for controllingcall volume in a packet network.

SUMMARY OF THE INVENTION

Method and apparatus for controlling call volume in a packet-switchednetwork is described. In one embodiment, a number of concurrent callsper codec of a plurality of codecs is monitored. A concurrent call limitfor each of the plurality of codecs is obtained. For each codec of theplurality of codecs, an indication is generated for each call causingthe number of concurrent calls for the codec to exceed the concurrentcall limit for the codec. In response to the indication, the call may beblocked or an alternative codec may be selected for the call.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 is a block diagram depicting an exemplary embodiment of acommunication system in accordance with the invention;

FIG. 2 is a block diagram depicting an exemplary embodiment of a portionof the communication system of FIG. 1 in accordance with one or moreaspects of the invention;

FIG. 3 is a flow diagram depicting an exemplary embodiment of a methodfor controlling call volume in a packet network in accordance with oneor more aspects of the invention; and

FIG. 4 is a block diagram depicting an exemplary embodiment of acomputer suitable for implementing the processes and methods describedherein.

DETAILED DESCRIPTION

To better understand the present invention, FIG. 1 illustratescommunication architecture 100 comprising an example network, e.g., apacket network such as a Voice over Internet Protocol (VOIP) network,related to the present invention. Exemplary packet networks includeinternet protocol (IP) networks, asynchronous transfer mode (ATM)networks, frame-relay networks, and the like. An IP network is broadlydefined as a network that uses Internet Protocol to exchange datapackets. Thus, a VoIP network or a SoIP (Service over Internet Protocol)network is considered an IP network.

In one embodiment, the VoIP network may comprise various types ofcustomer endpoint devices connected via various types of access networksto a carrier (a service provider) VoIP core infrastructure over anInternet Protocol/Multi-Protocol Label Switching (IP/MPLS) based corebackbone network. Broadly defined, a VoIP network is a network that iscapable of carrying voice signals as packetized data over an IP network.The present invention is described below in the context of anillustrative VoIP network. Thus, the present invention should not beinterpreted to be limited by this particular illustrative architecture.

Referring to FIG. 1, the customer endpoint devices can be either TimeDivision Multiplexing (TDM) based or IP based. TDM based customerendpoint devices 122, 123, 134, and 135 typically comprise of TDM phonesor Private Branch Exchange (PBX). IP based customer endpoint devices 144and 145 typically comprise IP phones or IP PBX. The Terminal Adaptors(TA) 132 and 133 are used to provide necessary interworking functionsbetween TDM customer endpoint devices, such as analog phones, and packetbased access network technologies, such as Digital Subscriber Loop (DSL)or Cable broadband access networks. TDM based customer endpoint devicesaccess VoIP services by using either a Public Switched Telephone Network(PSTN) 120, 121 or a broadband access network 130, 131 via a TA 132 or133. IP based customer endpoint devices access VoIP services by using aLocal Area Network (LAN) 140 and 141 with a VoIP gateway or router 142and 143, respectively.

The access networks can be either TDM or packet based. A TDM PSTN 120 or121 is used to support TDM customer endpoint devices connected viatraditional phone lines. A packet based access network, such as FrameRelay, ATM, Ethernet or IP, is used to support IP based customerendpoint devices via a customer LAN, e.g., 140 with a VoIP gateway androuter 142. A packet based access network 130 or 131, such as DSL orCable, when used together with a TA 132 or 133, is used to support TDMbased customer endpoint devices.

The core VoIP infrastructure comprises of several key VoIP components,such as the Border Elements (BEs) 112 and 113, the Call Control Element(CCE) 111, VoIP related Application Servers (AS) 114, and Media Servers(MS) 115. The BE resides at the edge of the VoIP core infrastructure andinterfaces with customers endpoints over various types of accessnetworks. A BE is typically implemented as a Media Gateway and performssignaling, media control, security, and call admission control andrelated functions. The CCE resides within the VoIP infrastructure and isconnected to the BEs using the Session Initiation Protocol (SIP) overthe underlying IP/MPLS based core backbone network 110. The CCE istypically implemented as a Media Gateway Controller or a softswitch andperforms network wide call control related functions as well asinteracts with the appropriate VoIP service related servers whennecessary. The CCE functions as a SIP back-to-back user agent and is asignaling endpoint for all call legs between all BEs and the CCE. TheCCE may need to interact with various VoIP related Application Servers(AS) in order to complete a call that require certain service specificfeatures, e.g. translation of an E.164 voice network address into an IPaddress and so on.

For calls that originate or terminate in a different carrier, they canbe handled through the PSTN 120 and 121 or the Partner IP Carrier 160interconnections. For originating or terminating TDM calls, they can behandled via existing PSTN interconnections to the other carrier. Fororiginating or terminating VoIP calls, they can be handled via thePartner IP carrier interface 160 to the other carrier.

In order to illustrate how the different components operate to support aVoIP call, the following call scenario is used to illustrate how a VoIPcall is setup between two customer endpoints. A customer using IP device144 at location A places a call to another customer at location Z usingTDM device 135. During the call setup, a setup signaling message is sentfrom IP device 144, through the LAN 140, the VoIP Gateway/Router 142,and the associated packet based access network, to BE 112. BE 112 willthen send a setup signaling message, such as a SIP-INVITE message if SIPis used, to CCE 111. CCE 111 looks at the called party information andqueries the necessary VoIP service related application server 114 toobtain the information to complete this call. In one embodiment, theApplication Server (AS) functions as a back-to-back user agent. If BE113 needs to be involved in completing the call; CCE 111 sends anothercall setup message, such as a SIP-INVITE message if SIP is used, to BE113. Upon receiving the call setup message, BE 113 forwards the callsetup message, via broadband network 131, to TA 133. TA 133 thenidentifies the appropriate TDM device 135 and rings that device. Oncethe call is accepted at location Z by the called party, a callacknowledgement signaling message, such as a SIP 200 OK response messageif SIP is used, is sent in the reverse direction back to the CCE 111.After the CCE 111 receives the call acknowledgement message, it willthen send a call acknowledgement signaling message, such as a SIP 200 OKresponse message if SIP is used, toward the calling party. In addition,the CCE 111 also provides the necessary information of the call to bothBE 112 and BE 113 so that the call data exchange can proceed directlybetween BE 112 and BE 113. The call signaling path 150 and the callmedia path 151 are illustratively shown in FIG. 1. Note that the callsignaling path and the call media path are different because once a callhas been setup up between two endpoints, the CCE 111 does not need to bein the data path for actual direct data exchange.

Media Servers (MS) 115 are special servers that typically handle andterminate media streams, and to provide services such as announcements,bridges, transcoding, and Interactive Voice Response (IVR) messages forVoIP service applications.

Note that a customer in location A using any endpoint device type withits associated access network type can communicate with another customerin location Z using any endpoint device type with its associated networktype as well. For instance, a customer at location A using IP customerendpoint device 144 with packet based access network 140 can callanother customer at location Z using TDM endpoint device 123 with PSTNaccess network 121. The BEs 112 and 113 are responsible for thenecessary signaling protocol translation, e.g., SS7 to and from SIP, andmedia format conversion, such as TDM voice format to and from IP basedpacket voice format.

FIG. 2 is a block diagram depicting an exemplary embodiment of a portion200 of the communication system 100 of FIG. 1 in accordance with one ormore aspects of the invention. In the portion 200, the core network 110includes a BE 204, a CCE 206, a BE 208, and an application server 216.An endpoint device 202 is coupled to the BE 204. An endpoint device 210is coupled to the BE 208. Each of the endpoint devices 202 and 210 iscoupled to the core network 110 using any of the various access networksdescribed above.

The endpoint device 202 includes a plurality of codecs 212 forprocessing media streams originated or received therein. Likewise, theendpoint device 210 includes a plurality of codecs 214. For example, acall established between the endpoint device 202 and the endpoint device214 may include one or more media streams, such as audio stream(s)(e.g., voice stream), video streams(s), and/or data stream(s). Thecodecs 212 and 214 are used to code the media stream(s) for transmissionthrough the core network 110, and to decode the media stream(s) uponreceipt from the core network 110. The codecs 212 and 214 may includeany type of codecs known in the art for processing audio, video, and/ordata. The codecs 212 and 214 may be compressing codecs (i.e., the datais compressed before transmission and uncompressed upon receipt) ornon-compressing codecs. The codecs 212 and 214 may be lossless codecs(i.e., none of the source data is lost during coding) or lossy codecs(i.e., some of the data is lost during coding). Exemplary audio codecsinclude audio interchange file format (AIFF), moving pictures expertgroup (MPEG) audio layer 3 (MP3), Windows Media Audio (WMA), and thelike. Exemplary voice codecs include G.711, G.722.1, G.723.1, G.729a,and the like. Exemplary video codecs include MPEG-4, H.264, and thelike.

Some codecs require more bandwidth in the core network 110 than othercodecs. In particular, lossless codecs require more bandwidth than lossycodecs. For example, most calls handled by the core network 110 mayinclude a voice stream. If a G.711 codec is used to code the voicestream, the core network 110 must allocate more bandwidth to the callthan if a G.723.1 codec was used, for example. In accordance with oneembodiment of the invention, the core network 110 employs concurrentcall limits on a per codec basis.

In one embodiment, the CCE 206 includes a controller 220. The CCE 206 isconfigured with threshold data 222. The threshold data 222 includesconcurrent call limits for each of a plurality of codecs. A concurrentcall limit is a maximum number of allowable calls at a time. Thecontroller 220 is configured to monitor numbers of concurrent callsprocessed by the CCE 206 for various codecs. If, for any codec, a callcauses the number of concurrent calls for that codec to exceed theconcurrent call limit for that codec, the controller 220 generates anindication. In response to each indication, the CCE 106 may block thecall that generated the indication. Alternatively, in response to eachindication, the CCE 106 may signal selection of an alternative codec forthe call that generated the indication.

Operation of the invention may be understood with reference to thefollowing example. Assume the endpoint device 202 is the originator of avoice call destined for the endpoint device 210. Assume further that SIPsignaling is used for call setup. The endpoint device 202 sends aSIP-INVITE to the BE 204. The SIP-INVITE includes an attributeindicating the desired codec. For example, the SIP-INVITE message mayact as a carrier for a session description protocol (SDP) message thatdescribes the media content of the call, including what codec is to beused. Assume the endpoint device 202 selects a G.711 codec for the call.The BE 204 sends a SIP-INVITE message to the CCE 206.

The CCE 206 processes the SIP-INVITE message to identify the codec to beused for the call. The controller 220 has hitherto been monitoring anumber of concurrent calls per codec of a plurality of codecs. Thecontroller 220 determines whether the call will cause the number ofconcurrent calls for the identified codec to exceed the concurrent calllimit for that codec. If not, the CCE 206 sends a SIP-INVITE message tothe BE 208 and nominal call processing continues, as described above.Otherwise, the controller 220 generates an indication that the requestedcall exceeds a concurrent call limit for the identified codec.

In one embodiment, the CCE 206 may block the call in response to theindication. In another embodiment, the CCE 206 may send a SIP signalingmessage to the BE 204 indicating that an alternative codec must beselected in order to complete the call. The BE 204 in turn forwards theSIP signaling message to the endpoint device 202, which may selectanother codec for completing the call. The CCE 206 may provide asuggested codec to the endpoint device 202. The suggested codec may bebased on the numbers of concurrent calls currently established for thecodecs as compared to the respective concurrent call limits.

In another example, the SIP-INVITE message generated by the endpointdevice 202 may include a list of desired codecs in order of desirability(e.g., the list may include a first desired codec, followed by one ormore alternative codecs). If the controller 220 generates an indicationthat the call would cause the number of concurrent calls to exceed thecorresponding call limit for the first codec in the list, the CCE 206may select the next codec in the list for the call. The controller 220then determines whether the call will cause the number of concurrentcalls for the next codec to exceed the concurrent call limit for thatcodec. The process may proceed in this manner until a codec is selectedwhere the call does not cause a concurrent call limit to be exceeded, orthere are not more alternative codecs to select. If a codec is selectedthat does not cause a concurrent call limit to be exceeded, the CCE 206sends a SIP-INVITE message to the BE 208 with the selected codec andcall processing continues. Otherwise, the CCE 206 may block the call orsend a SIP signaling message towards the endpoint device 202 indicatingthat an alternative codec must be selected. The CCE 206 may provide asuggested codec.

For purposes of clarity by example, aspects of the invention have beendescribed with respect to SIP signaling. It is to be understood thatother types of signaling may be employed. In general, the endpointdevice 202 signals a call request to the network 110 that includes oneor more requested codecs. In the embodiments described above, the CCE206 is configured with the controller 220 and the threshold data 222.Those skilled in the art will appreciate that the controller 220 and thethreshold data 222 may be configured in other types of network elementsthat process calls in the core network 110, such as border elements(e.g., BEs 204 and 208). In addition, in the embodiments describedabove, the call included only a voice stream. Those skilled in the artwill appreciate that the call may include other types of media streams.Processing proceeds as described above, but with other types of codecs.

In the embodiments described above, the endpoint device 202 selects oneor more codecs for the call. In another embodiment, the setup signalingmessage sent by endpoint device 202 does not include selected codec(s).Rather, the network 110 is configured to select a codec for the call.For example, upon receiving the setup signaling message from theendpoint device 202, the BE 204 forwards the message to the CCE 206. TheCCE 206 selects one or more codecs for the call. The controller 220 hashitherto been monitoring a number of concurrent calls per codec of aplurality of codecs. The controller 220 generates an indication for eachcodec where the call will cause the concurrent call limit for that codecto be exceeded. In this manner, the CCE 206 formulates a list of one ormore allowable codecs to be used by the call. In one embodiment, the CCE206 sends a signaling message to the BE 204 with the list of allowablecodec(s), which forwards the message to the endpoint device 202. If thelist of codec(s) is satisfactory to the endpoint device 202, then callprocessing proceeds. In another embodiment, the CCE 206 may justproceeds with call processing without seeking authorization from theendpoint device 202. Again, while this example has been described withrespect to the CCE 206, those skilled in the art will appreciate thatthis functionality may be employed by other network elements, such asBEs.

In one embodiment, the concurrent call limit for at least one of theplurality of codecs in the threshold data 222 is adjusted in response tomeasures of traffic volume. For example, the application server 216 maybe configured with a traffic analyzer 218. The traffic analyzer 218 isconfigured to generate measures of traffic volume in the network 110over time. The controller 220 may obtain these measures of trafficvolume from the application server 216. The concurrent call limits maybe dynamically adjusted as a function of the traffic volume measures.For example, if traffic volume is high, concurrent call limits forlossless codecs may be decreased to conserve bandwidth. This decreasingof concurrent call limits may be paired with an increase in concurrentcall limits for lossy codecs. Conversely, if traffic volume is low,concurrent call limits for lossless codecs may be increased. While thetraffic analyzer 218 is implemented by the application server 216, it isto be understood that the traffic analyzer 218 may be implemented inother network elements, such as CCEs (e.g., the CCE 206), BEs (e.g., BEs204 and 208), and the like.

FIG. 3 is a flow diagram depicting an exemplary embodiment of a method300 for controlling call volume in a packet network in accordance withone or more aspects of the invention. The method 300 begins at step 302,where a call request is received. At step 304, a codec is identified forthe call. In one embodiment, the originating endpoint of the callprovides one or more potential codecs for the call. Alternatively, anetwork element in the network may provide one or more potential codecs.If multiple potential codecs are specified, one of them is identified atstep 304. At step 306, a determination is made whether the call wouldcause the concurrent call limit for the identified codec to be exceeded.Concurrent call limits for various codecs are obtained at step 310. Ifnot, the method 300 proceeds to step 308, where the call is processedusing the identified codec. The method 300 returns to step 302 andrepeats for another call request.

If the call would cause the concurrent call limit to be exceeded at step306, the method 300 proceeds to step 312. At step 312, an indication ofthat a concurrent call limit has been exceeded is generated. At step314, the call is blocked or an alternative codec is selected for thecall in response to the indication. The alternative codec may beselected by the network, or the network may signal the originatingendpoint to select another codec. The method 300 returns to step 302 andrepeats for another call.

FIG. 4 is a block diagram depicting an exemplary embodiment of acomputer 400 suitable for implementing the processes and methodsdescribed herein. The computer 400 includes a central processing unit(CPU) 401, a memory 403, various support circuits 404, and an I/Ointerface 402. The CPU 401 may be any type of microprocessor known inthe art. The support circuits 404 for the CPU 401 include conventionalcache, power supplies, clock circuits, data registers, I/O interfaces,and the like. The I/O interface 402 may be directly coupled to thememory 403 or coupled through the CPU 401. The I/O interface 402 may becoupled to various input devices 412 and output devices 411, such as aconventional keyboard, mouse, printer, and the like.

The memory 403 may store all or portions of one or more programs and/ordata to implement the processes and methods described herein. Notably,the memory 403 may store program code to be executed by the CPU 401 forperforming the processes and methods described herein. Although one ormore aspects of the invention are disclosed as being implemented as acomputer executing a software program, those skilled in the art willappreciate that the invention may be implemented in hardware, software,or a combination of hardware and software. Such implementations mayinclude a number of processors independently executing various programsand dedicated hardware, such as ASICs.

The computer 400 may be programmed with an operating system, which maybe OS/2, Java Virtual Machine, Linux, Solaris, Unix, Windows, Windows95,Windows98, Windows NT, and Windows2000, WindowsME, and WindowsXP, amongother known platforms. At least a portion of an operating system may bedisposed in the memory 403. The memory 403 may include one or more ofthe following random access memory, read only memory, magneto-resistiveread/write memory, optical read/write memory, cache memory, magneticread/write memory, and the like, as well as signal-bearing media asdescribed below.

An aspect of the invention is implemented as a program product for usewith a computer system. Program(s) of the program product definesfunctions of embodiments and can be contained on a variety ofsignal-bearing media, which include, but are not limited to: (i)information permanently stored on non-writable storage media (e.g.,read-only memory devices within a computer such as CD-ROM or DVD-ROMdisks readable by a CD-ROM drive or a DVD drive); (ii) alterableinformation stored on writable storage media (e.g., floppy disks withina diskette drive or hard-disk drive or read/writable CD or read/writableDVD); or (iii) information conveyed to a computer by a communicationsmedium, such as through a computer or telephone network, includingwireless communications. The latter embodiment specifically includesinformation downloaded from the Internet and other networks. Suchsignal-bearing media, when carrying computer-readable instructions thatdirect functions of the invention, represent embodiments of theinvention.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

1. A method of controlling call volume in a packet network, comprising:monitoring a number of concurrent calls per codec of a plurality ofcodecs; obtaining a concurrent call limit for each of the plurality ofcodecs; and generating, for each codec of the plurality of codecs, anindication for each call causing the number of concurrent calls for thecodec to exceed the concurrent call limit for the codec.
 2. The methodof claim 1, further comprising: blocking, in response to each generatedindication, the call corresponding to the generated indication.
 3. Themethod of claim 1, further comprising: selecting, in response to eachgenerated indication, an alternative codec of the plurality of codecsfor the call corresponding to the generated indication.
 4. The method ofclaim 1, further comprising: obtaining measures of traffic volume overtime; and adjusting the concurrent call limit for at least one of theplurality of codecs in response to each of the measures of trafficvolume.
 5. The method of claim 4, wherein, for each measure of trafficvolume of the measures of traffic volume, the concurrent call limit forthe at least one of the plurality of codecs is decreased if the measureof traffic volume is more than a previous measure of traffic volume. 6.The method of claim 1, wherein the plurality of codecs includes at leastone lossless codec and at least one lossy codec.
 7. The method of claim1, wherein the packet network comprises a voice over internet protocol(VOIP) network or a services over internet protocol (SOIP) network. 8.Apparatus for controlling call volume in a packet network, comprising:means for monitoring a number of concurrent calls per codec of aplurality of codecs; means for obtaining a concurrent call limit foreach of the plurality of codecs; and means for generating, for eachcodec of the plurality of codecs, an indication for each call causingthe number of concurrent calls for the codec to exceed the concurrentcall limit for the codec.
 9. The apparatus of claim 8, furthercomprising: means for blocking, in response to each generatedindication, the call corresponding to the generated indication.
 10. Theapparatus of claim 8, further comprising: means for selecting, inresponse to each generated indication, an alternative codec of theplurality of codecs for the call corresponding to the generatedindication.
 11. The apparatus of claim 8, further comprising: means forobtaining measures of traffic volume over time; and means for adjustingthe concurrent call limit for at least one of the plurality of codecs inresponse to each of the measures of traffic volume.
 12. The apparatus ofclaim 11, wherein, for each measure of traffic volume of the measures oftraffic volume, the concurrent call limit for the at least one of theplurality of codecs is decreased if the measure of traffic volume ismore than a previous measure of traffic volume.
 13. The apparatus ofclaim 8, wherein the plurality of codecs includes at least one losslesscodec and at least one lossy codec.
 14. The apparatus of claim 8,wherein the packet network comprises a voice over internet protocol(VOIP) network or a services over internet protocol (SOIP) network. 15.A computer readable storage medium having stored thereon instructionsthat, when executed by a processor, cause the processor to perform amethod of controlling call volume in a packet network, comprising:monitoring a number of concurrent calls per codec of a plurality ofcodecs; obtaining a concurrent call limit for each of the plurality ofcodecs; and generating, for each codec of the plurality of codecs, anindication for each call causing the number of concurrent calls for thecodec to exceed the concurrent call limit for the codec.
 16. Thecomputer readable storage medium of claim 15, further comprising:blocking, in response to each generated indication, the callcorresponding to the generated indication.
 17. The computer readablestorage medium of claim 15, further comprising: selecting, in responseto each generated indication, an alternative codec of the plurality ofcodecs for the call corresponding to the generated indication.
 18. Thecomputer readable storage medium of claim 15, further comprising:obtaining measures of traffic volume over time; and adjusting theconcurrent call limit for at least one of the plurality of codecs inresponse to each of the measures of traffic volume.
 19. The computerreadable storage medium of claim 15, wherein the plurality of codecsincludes at least one lossless codec and at least one lossy codec. 20.The computer readable storage medium of claim 15, wherein the packetnetwork comprises a voice over internet protocol (VOIP) network or aservices over internet protocol (SOIP) network.